You might not know what they're called, but you've definitely seen loads of them: Gifs, those little animations playing on a loop that crop up all over the web. People use them as moving Twitter profile pics, or juddering web-forum avatars. They can be built from homemade graphics or TV screen grabs. They're often funny, more often annoying and, just occasionally, inspired. And presently, they're everywhere.

Gif is, baldly considered, a file format, and an old one at that. The Graphics Interchange Format was first developed by CompuServe in 1987, to allow for the quick downloading of highly compressed colour images. It also supported animation, which eventually became its defining feature, particularly the repeating animations introduced with the Netscape Navigator 2.0 browser. In the beginning Gifs were largely confined to either rotating things or flaming things, but they quickly became more complex.

By the turn of the century the Gif had become distinctly unfashionable, but within a few years its retro appeal (Gifs often retain the look of a well-thumbed flip book) and simplicity (anyone can make their own these days; well, not me) saw a resurgence in popularity. What was the height of naffness at the end of the web 1.0 era is now a cool, lo-fi mode of self-expression. Thanks largely to the rise of Tumblr, the humble file format has become a form. These days Gifs range from small, repeating film grabs embedded into blogs as a sort of illustrative punctuation, to the spectral Cinemagraphs of Jamie Beck and Kevin Burg. There are news Gifs created to illuminate the week's events, or merely to highlight some new aspect of Mitt Romney's unfortunate manner.

For such a venerable format (the patent for its file-compression algorithm expired in 2004), it is curious that one question should remain unsettled: how do you pronounce Gif? The hard G of "graphics" should probably transfer to the acronym, although the original specifications for the format made a point of mentioning that it was pronounced "jif". Among users the latter pronunciation seems to have far more adherents, but the dissenting minority is no less certain of its correctness. Don't ask me; I don't even have an opinion.